Fuel economy has improved after a week at the dealer

[o0260o]

I am not sure what happened with my '21 BB. I had the car in for a failed ignition coil. When I got it back I noticed they did the recall catheter thing and replaced a cylinder deactivation solenoid. The coil that was causing a misfire was changed too. Now, my avg MPG is up to 29 from 27. Doing the same route every day.
So what is going on? Did the failing ignition coil mess with economy. I've had consistent mpg for past 2 years. Did the ECU reprogramming that is part of the recall make it more efficient? Is the onboard estimator made more accurate? Or did the cylinder deactivation never actually worked for me? I would think that would give a code or CEL if it failed to deactivate a cylinder. Thoughts?

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[Mark S.]

I wouldn't take what the computer is telling you as gospel. Run a few tanks through it and keep track of how many miles you get. It'll take an average over three tanks full to get an accurate hand-measured mpg figure.